tectonics montoring and mitigating

earthquake prediction

United States Geological Survey says prediction should define date, time , location and magnitude

methods to monitor

• tilt meter and gravity meter to detect changes in the local magnetic field and minor earth movements

• creep meter to monitor small movements along the fault

• radon gas counter; the amount of radon gas dissolved in groundwater has been shown to increase before some earthquakes

• strain meter to monitor stress changes in the rocks

example of successful monitoring

Helpful on a local scale as seen in 1975 Heichang earthquake was successfully forecast 5 ½ hours before the event allowing 90,000 people to be successfully evacuated HOWEVER the Great Tangshan earthquake of 19976 was totally unexpected and resulted in huge death toll

monitoring volcanic eruptions

• Seismic activity may show an increase suggesting rising magma

• Tilt meters and laser measures can detect minute changes in slope angle and the distance between points, suggesting rising magma is displacing ground above

• Detectors, including satellites, can register changes in temp at the surface and in lakes suggesting an increase in activity

successful volcano monitoring

Monitoring cannot predict the increased likelihood of an eruption as cannot give an accurate prediction of date/time/location and magnitude but can allow plans to be prepared. Pinatubo in 1991 resulted in most hazardous zone being officially evacuated over 2 months before eruption and a larger area just 2 days before.

monitoring tsunami

• Scientists can only do by monitoring undersea seismic activity

• Tide gauges, tsunam detection buoys and pressure recorders located on the ocean bottom are used to record changes that show a tsunami has been generated

• Once a tsunami is generated, areas can be warned of its arrival. Pacific tsunami warning system coordinates tsunami threat warnings throughout the Pacific and has been issuing warnings for 70 years, allowing evasive action to take place

successful monitoring of tsunami

No Indian Ocean warning system in place before 2004 tsunami. In 2005 was established and became fully operative by 2011. Helps between 1.5 to 2 billion people in 28 countries. Paid for by UNESCO and India and allows to predict risk to coastal aras, height of waves and pinpoint areas of vulnerability. HOWEVER, tsunami may destroy power and communication lines so warning cant be recieved/occur too quickly/not be supported by effective evacuation routes and community education

Issue with volcano monitoring and prediction

Length of time available for evacuation is unpredictable and sometimes false alarms. Montserrat, 5,000 residents were evacuated 3 times between dec 1995 and aug 1996.

Also unable to predict secondary hazards

mitigating hzard impact

as parks model states: modify event, modify loss and modify vulnerability

Modifying the event

Volcanic eruptions - control flow of lava as seen Heimaey poured 7bil litres of sea water AND barriers diverting lava flows away from villages as seen on Mt Etna in Sicily in 1991

Earthquakes - Not yet possible

Tsunamis - coastal defences as seen in Japan 400km chain of sea walls, redevelopment of mangroves to protect rural areas by dissipating the wave energy.

Modifying the vulnerability

Eruptions - hazard mapping to know areas at risk of lahar/lava which can inflluence land use planning and zoning, education so community knows how to prepare

Earthquake - Aseismic buildings BUT old buildings have to be retrofitted + expensive + harder to enforce in poorer countries, education and earthquake drills, hazard mapping, smart technology which sends short term warnings

Tsunamis - Education, evacuation routes, coastal zone management and land use planning

Modifying the loss

All - rescue and relief efforts, aid from govts and NGOs, emergency survival kits

Management of a hazard

Hazard management cycle. Event—>respond—> recover—> prevent—> prepare

Immediate relief affected by

type of hazard

geographical accessibility

climate

topography

number of people involved

degree of community preparedness

technological resources

education and training

Wealth and infrastructure

rehabilitation

wealth of coutnry + preparedness of govt

Park’s disaster response curve

Different curves for different countries as depends on vulnerability of people, quality of responses, preparedness, wealth